A problem has arisen in the past with respect to intraocular lenses, in that the lens itself has a diameter of the order of 6 millimeters, and the surgeon would prefer to use a smaller incision, because the smaller the incision the more rapid the healing, resulting in more rapid visual and physical rehabilitation and fewer complications. There is also less astigmatism, less discomfort to the patient, a shorter operating time, and thus a reduced cost, when a small incision is used.
A deformable intraocular flexible lens has recently been developed for implantation into the eye. Such a lens is inserted into the eye through a small incision made by the surgeon in the sclera or cornea. A typical insertion method is described, for example, in Mazzocco U.S. Pat. No. 4,573,998.
The deformable intraocular lens referred to above may be deformed to a reduced configuration for insertion into the eye through a relatively small incision. However, the deformable intraocular lens, like other intraocular lenses, includes haptics or loops which serve to secure the lens in position after it has been inserted into the eye. These haptics or loops, as well as the optical zone of the lens, are fragile, and they have a tendency to tear when attempts are made to deform the lens for insertion purposes. If a lens is damaged during insertion the incision must be enlarged to allow the first lens to be removed and a second lens to be inserted. This poses a significant problem in devising a suitable instrument for deforming the lens prior to insertion through the small incision, and one which has no tendency to damage the lens during the deformation process.
Prior art attempts to provide insertion instruments which do not tend to tear off the haptics or loops, or to otherwise damage the lens, have, for the most part, proven to be somewhat unsuccessful.
One such prior art instrument, for example, requires that the lens be loaded by hand during the surgical procedure and inserted into a tube. A reduction nozzle is then screwed onto the tube, and a viscoelastic material is introduced into the other end of the tube by means of a syringe, thereby forcing the lens into and through the reduction nozzle. In this manner, the lens is forced into a smaller and smaller cylinder, under pressure created by the syringe forcing the viscoelastic material against the lens, until the lens is finally released from the nozzle at a relatively high speed into the eye through a 3 to 3.5 millimeter incision. When this prior art instrument is used, the lens frequently tears during the insertion process.
A second prior art instrument is similar to the one described in the preceding paragraph, except that a clam-like hinged tube is employed to help form the lens into a tubular or rolled configuration. However, as the hinged tube is closed, there is a tendency to crimp the lens and damage it.
Both prior art instruments described above require hand loading of the lens. However, any handling of the lens has a tendency to damage it. Moreover, powder from surgical gloves, and other foreign particles, can contaminate the lens. In addition, both prior art instruments described above subject the lens to a substantial pressure as the lens is forced along and squeezed down the tube into the eye.
An objective of the present invention is to provide a simple, inexpensive instrument, which may be disposable, for deforming the lens and thereby reducing its configuration without any need for the surgeon or assistant to handle or touch the lens, and which permits the insertion of the lens into the eye through a small incision, all without any tendency to tear off the haptics or loops or otherwise to damage or contaminate the lens.
The present invention is generally similar in some respects to the instrument described in Hauser U.S. Pat. No. 4,763,650 which issued Aug. 16, 1988.